Reverse input blocking clutch and clutch device using the same

ABSTRACT

A reverse input blocking clutch comprises, as main elements, an input member, an output member, a stationary member for constraining the revolutions, locking means, lock release means and torque transmission means. By forming the input member, the output member, the stationary member and a fixed side plate from metal plates such as press worked steel plates, a compact, lightweight and low cost reverse input blocking clutch is provided. Reverse input torque from the output member is locked in both the forward and reverse rotational directions relative to the stationary member, by rollers which function as the locking means. Input torque from the input member in both the forward and reverse rotational directions is transmitted to the output member via apertures  1   d  and protrusions which function as the torque transmission means.

This is a Division of application Ser. No. 10/091,593 filed Mar. 7,2002, now U.S. Pat. No. 6,695,118. The disclosure of the priorapplication is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

In devices which perform a desired operation by transmitting inputtorque from a rotational driving source such as a motor to an outputmechanism, when the driving source is stopped, there are occasions inwhich it is desirable to block the transmission of reverse input torquefrom the output mechanism back to the input side.

An example of such an occasion is when a retention function is employedto prevent the position of the output mechanism fluctuating when thedriving source is stopped. In this type of device, taking an electricshutter as an example, the input torque from the driving motor in eithera forward or reverse direction is input to an opening and closingmechanism on the output side, which then performs the operation foreither opening or closing the shutter, although if for some reason (suchas a power failure or the like) the driving motor is stopped partwaythrough the opening or closing operation, reverse input torque resultingfrom the descent of the shutter under its own weight is returned to theinput side, resulting in the possibility of damage to the input sidecomponents. Consequently, a mechanism is required which holds theposition of the shutter, and prevents the return of reverse input torquefrom the shutter to the input side.

Furthermore, in a construction in which a reduction gear is used toreduce the revolutions of a motor, the following problems may arise inthose cases where, for some reason, torque is reverse input from theoutput side.

(a) In a case in which worm gearing is used as the reduction gear, thenbecause rotation under reverse input is impossible with this type ofworm gearing, a very large load is exerted on the worm wheel or theteeth of the worm. In particular, a very large thrust loading acts uponthe worm. As a result, there is a danger of damage to the bearingsupporting the teeth and the worm, or alternatively, the mechanism mustbe increased in size in order to prevent this type of damage.

(b) Even in the case of a reduction gear which utilizes a spur gear or ahelical gear, there is still a possibility of damage to the teeth inthose cases where the reverse input torque becomes excessively large(such as the case of a shocking reverse input).

In order to resolve the problems outlined above, a mechanism is requiredwhich is capable of transmitting input torque from the motor of theinput side to the output side, but also capable of locking the outputside with respect to reverse input torque from the output side, therebypreventing the return of reverse input torque to the motor or thereduction gear on the input side.

Furthermore in recent years, many vehicles including automobiles havebeen equipped with motor driven electric retractable door mirrors,wherein the mirror moves through an angle of approximately 90° between aworking position in which the mirror protrudes out from the side of thevehicle, and a retracted storage position. A conventional electricretractable door mirror (such as that disclosed in Japanese PatentLaid-Open Publication No. Hei 11-51092) utilizes a driving mechanismsuch as that shown in FIG. 29, wherein a mirror 42 can be moved easilyby driving a motor 41, but when an external force acts upon the mirror42, a clutch 43 effectively blocks the external force, holding themirror 42 firmly in place and preventing the external force from actingupon the motor 41.

However, in the driving mechanism disclosed in the above publication,because the mirror is securely fixed and undergoes no rotation even ifan external force results in a reverse input torque acting upon themirror, the mechanism is unable to absorb such an external force, andthe mirror is consequently prone to damage. In order to resolve thisproblem, a mechanism is required which is capable of transmitting inputtorque from the motor of the input side to the mirror of the outputside, but also permits the mirror to slip with respect to reverse inputtorque, thereby blocking the transmission of such reverse input torqueback to the input side.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a reverse inputblocking clutch which has the functions described above, and yet iscompact, lightweight and low cost, as well as a clutch device using sucha reverse input blocking clutch.

In order to achieve this object, a reverse input blocking clutch of thepresent invention comprises an input member into which torque is input,an output member to which torque is output, a stationary member forconstraining the revolutions, locking means provided between thestationary member and the output member for locking the output memberand the stationary member with respect to reverse input torque from theoutput member, lock release means provided on the input member forreleasing a locked state produced by the locking means with respect toinput torque from the input member, and torque transmission meansprovided between the input member and the output member for transmittinginput torque from the input member to the output member when the lockedstate produced by the locking means is released, wherein at least theinput member from amongst the input member, the output member and thestationary member is produced by deformation processing of a metalplate.

The “locking means” described above incorporates a device which appliesan antirotation force by means of a wedge engagement force, anengagement between concave and convex surfaces, frictional force,magnetic force, electromagnetic force, fluid pressure, fluid viscosityresistance or a fine particle medium or the like, although from theviewpoints of cost, the simplicity of the structure and the controlmechanism, and the smoothness of operation a device which applies anantirotation force by means of a wedge engagement force is preferred.

Specifically, a wedge shaped gap is formed between the output member andthe stationary member, and an engagement member is then either engagedinto, or disengaged from this gap to switch the device between a lockedstate and a slipping state respectively. Furthermore, this type ofconstruction includes structures in which a cam surface for forming thewedge shaped gap is provided on either the output member or thestationary member (and an engagement member with a circular crosssection such as a roller or a ball is used), and structures in which acam surface for forming the wedge shaped gap is provided on theengagement member (and a sprag or the like is used as the engagementmember).

Furthermore, the “metal plate” described above may be any metal platecapable of being shaped by deformation processing to the desired shapeand dimensions. There are no particular restrictions on the materialused, and a steel plate is a suitable example. Furthermore, thedeformation processing can utilize techniques such as press working.

According to the above construction, when input torque is input at theinput member, first the locked state produced by the locking means isreleased by the lock release means, and with the device in this releasedstate, the input torque from the input member is transmitted to theoutput member via the torque transmission means. In contrast, a reverseinput torque from the output member is locked between the output memberand the stationary member by the locking means. Accordingly, a functionis achieved wherein input torque from the input side is transmitted tothe output side, whereas reverse input torque from the output side isnot returned to the input side. Furthermore, by producing at least theinput member from amongst the input member, the output member and thestationary member, from a metal plate which has undergone deformationprocessing, then in comparison with forged products, cast products orcutout products, the device is more compact, lighter, and cheaper toproduce.

In the above construction, a connector can be provided for connecting aninput shaft to the input member, and this connector can be positionedinside the clutch. As a result, the dimensions of the clutch itself inan axial direction can be kept compact, and furthermore the overalldimensions in an axial direction upon assembly with the rotationaldriving source can also be kept compact. This connector is preferablyprovided on a cylindrical section which extends in a continuous mannerfrom the inner perimeter of the input member towards the inside of theclutch, and is also provided with at least one flat surface sectionwhich engages with a flat surface on the input shaft. This engagementbetween the flat surface of the input shaft and the flat surface of theconnector causes the input shaft and the input member to be connected insuch a manner that prevents relative rotation.

Furthermore in the above construction, a cylindrical output shaftsection can also be incorporated into the output member. By so doing,the weight of the output shaft section can be reduced, the number ofcomponents can be reduced, and the production cost can be lowered. Theoutput shaft section should preferably be closed at one end. By sodoing, the strength of the output shaft section relative to a radialload or a torsional torque can be increased, and so deformation can beprevented and durability improved. Furthermore, the output shaft sectionshould also preferably comprise at least one flat surface which engageswith a flat surface of another driven member (a rotating member of amechanism or device connected to the output side). The engagementbetween the flat surface provided on this other driven member and theflat surface of the output shaft section causes the output shaft sectionand the other driven member to be connected in such a manner thatprevents relative rotation. Alternatively, a spline section or aserrated section which engages with a corresponding section on the otherdriven member could also be provided on the output shaft section.

In the above construction, the locking means can comprise acircumferential surface provided on the stationary member, a cam surfaceprovided on the output member for forming the wedge shaped gap in thedirections of both forward and reverse rotation between the outputmember and the circumferential surface, a pair of engagement memberspositioned between the cam surface and the circumferential surface, andan elastic member for pressing the pair of engagement members in thedirection of the wedge shaped gap, the lock release means can be anengagement element which engages with either one of the pair ofengagement members and pushes that engagement member in a direction awayfrom the wedge shaped gap, and the torque transmission means cancomprise rotational engagement elements provided on the input member andthe output member, wherein at the neutral positions of the lock releasemeans and the torque transmission means, the gap δ1 in the direction ofrotation between the engagement element of the lock release means andthe engagement member, and the gap δ2 in the direction of rotationbetween the engagement elements of the torque transmission means existin a relationship in which δ1<δ2.

According to the above construction, when a reverse input torque of onedirection is input at the output member, one of the pair of engagementmembers engages in the wedge shaped gap in that direction, and theoutput member is locked in that direction relative to the stationarymember. In contrast, when a reverse input torque of the other directionis input at the output member, the other one of the pair of engagementmembers engages in the wedge shaped gap in that direction, and theoutput member is locked in the other direction relative to thestationary member. Consequently, the output member is locked in both theforward and reverse rotational directions relative to the stationarymember by the actions of the pair of engagement members. In contrast,when input torque is input at the input member, first the engagementelement provided as the lock release means on the input member pushesthe engagement member which engages with the wedge shaped gap in thedirection of the torque away from the wedge shaped gap, disengaging theengagement member from the wedge shaped gap. As a result, the lockedstate of the output member is released relative to the direction of theinput torque. Subsequently, with the output member in this releasedstate, the rotational engagement elements provided on the input memberand the output member as the torque transmission means engage with oneanother. By so doing, the input torque input at the input member istransmitted from the input member to the torque transmission means (therotational engagement elements) and through to the output member,causing the output member to rotate.

By setting the relationship between the gap δ1 in the direction ofrotation between the engagement element of the lock release means andthe engagement member, and the gap δ2 in the direction of rotationbetween the engagement elements of the torque transmission means, sothat at the neutral positions of the lock release means and the torquetransmission means δ1<δ2, the lock release process provided by theaforementioned lock release means and the torque transmission processprovided by the torque transmission means can be carried outconsecutively and reliably.

In the above construction, the torque transmission means may comprise aconvex section provided on either one of the input member and the outputmember, and a matching concave section provided on the other member.Specifically, a protrusion comprising the convex section can be providedon the output member, and a notch or a cavity comprising the concavesection provided on the input member. In such a case, the protrusion mayeither protrude out in a radial direction or in an axial direction.Moreover, the cam surface may be formed directly on the output member,or alternatively a separate member with a cam surface may be attached tothe output member. Furthermore, a roller should preferably be used asthe engagement member.

In the above construction, the aforementioned elastic member couldcomprise a base and a tongue section extending from the base in eitherone of the axial directions, wherein the tongue section is positionedbetween the pair of engagement members and pushes the pair of engagementmembers mutually apart. The elastic member should preferably comprise anintegrated ring, namely, a ring shaped base with a plurality of tonguespositioned around the circumference of the ring, as such a structureenables a reduction in the number of components, and a consequentlowering of the production cost.

In the above construction, a fixed side plate can be fixed to thestationary member, with this fixed side plate produced from a metalplate which has undergone deformation processing. In such a case, thebearing supporting the input shaft in a radial direction can beintegrated into this fixed side plate. As a result, the operation ofrotating the input shaft and the input member can be performed smoothlyand with good stability, and the application of an unbalanced load tothe locking means can be prevented or suppressed, thereby enabling amore stable clutch operation. Moreover, although this bearing may alsobe constructed by providing a separate rolling bearing or slidingbearing, the integrated structure described above enables a simplerstructure and a reduced number of components. This bearing shouldpreferably be provided on a cylindrical section extending in acontinuous manner from the inner perimeter of the fixed side platetowards the inside of the clutch.

Furthermore in order to resolve the problems described above, a clutchdevice of the present invention is an integrated unit comprising arotational driving source and a reverse input blocking clutch. Thereverse input blocking clutch comprises an input member into whichtorque from the rotational driving source is input, an output member towhich torque is output, a stationary member for constraining therevolutions, locking means provided between the stationary member andthe output member for locking the output member and the stationarymember with respect to reverse input torque from the output member, lockrelease means provided on the input member for releasing a locked stateproduced by the locking means with respect to input torque from theinput member, and torque transmission means for transmitting inputtorque from the input member to the output member when the locked stateproduced by the locking means is released.

According to the above construction, when input torque from therotational driving source is input at the input member of the reverseinput blocking clutch, first the locked state produced by the lockingmeans is released by the lock release means, and with the device in thisreleased state, the input torque from the input member is transmitted tothe output member via the torque transmission means. In contrast, areverse input torque from the output member is locked between the outputmember and the stationary member by the locking means.

Accordingly, a function is achieved wherein input torque from the inputside is transmitted to the output side, whereas reverse input torquefrom the output side is not returned to the rotational driving source ofthe input side. Furthermore, by producing this reverse input clutch asan integrated unit with the rotational driving source, the deleteriouseffects of reverse input torque on the rotational driving source can beavoided, and a clutch device (rotational driving device) can be providedwhich is lightweight, Compact, and cheap to produce.

Furthermore, the same effects can be achieved with an integrated clutchdevice (rotational driven device) comprising (1) a reverse inputblocking clutch comprising an input member into which torque from therotational driving source is input, an output member to which torque isoutput, a stationary member for constraining the revolutions, lockingmeans provided between the stationary member and the output member forlocking the output member and the stationary member with respect toreverse input torque from the output member, lock release means providedon the input member for releasing a locked state produced by the lockingmeans with respect to input torque from the input member, and torquetransmission means for transmitting input torque from the input memberto the output member when the locked state produced by the locking meansis released, and (2) an output mechanism for performing a desiredoperation using the torque transmitted to the output member of thereverse input blocking clutch.

What is described above as a “rotational driving source” refers to adevice for generating rotational torque, and includes motors, engines,and hand operated members such as handles, as well as combinations ofsuch devices with reduction gears.

Furthermore, by producing at least the input member from amongst theinput member, the output member and the stationary member of the reverseinput blocking clutch, from a metal plate which has undergonedeformation processing, then in comparison with forged products, castproducts or cutout products, the device is more compact, lighter, andcheaper to produce.

In the above construction, a connector can be provided for connecting anoutput shaft of the rotational driving source to the input member, andthis connector can be positioned inside the clutch. As a result, thedimensions of the clutch itself in an axial direction can be keptcompact, and furthermore the overall dimensions of the aforementionedclutch device in an axial direction can also be kept compact. Thisconnector is preferably provided on a cylindrical section which extendsin a continuous manner from the inner perimeter of the input membertowards the inside of the clutch, and is also provided with at least oneflat surface section which engages with a flat surface on the outputshaft of the rotational driving source. This engagement between the flatsurface provided on the output shaft of the rotational driving sourceand the flat surface of the connector causes the output shaft and theinput member to be connected in such a manner that prevents relativerotation.

Furthermore, at least one flat surface which engages with a flat surfaceof a driven member of an output mechanism may also be provided on theoutput shaft section. The engagement between the flat surface providedon this driven member and the flat surface of the output shaft sectioncauses the output shaft and the other driven member to be connected insuch a manner that prevents relative rotation. Alternatively, a splinesection or a serrated section which engages with a corresponding sectionon the driven member of the output mechanism could also be provided onthe output shaft section.

In the above construction, the locking means of the reverse inputblocking clutch comprises a circumferential surface provided on thestationary member, a cam surface provided on the output member forforming a wedge shaped gap in the directions of both forward and reverserotation between the output member and the circumferential surface, apair of engagement members positioned between the cam surface and thecircumferential surface, and an elastic member for pressing the pair ofengagement members in the direction of the wedge shaped gap. The lockrelease means is an engagement element which engages with either one ofthe pair of engagement members and pushes that engagement member in adirection away from the wedge shaped gap, and the torque transmissionmeans comprises rotational engagement elements provided on the inputmember and the output member. At the neutral positions of the lockrelease means and the torque transmission means, the gap δ1 in thedirection of rotation between the engagement element of the lock releasemeans and the engagement member, and the gap δ2 in the direction ofrotation between the engagement elements of the torque transmissionmeans exist in a relationship in which δ1<δ2.

Furthermore, in order to resolve the problems described above, a clutchdevice according to the present invention is a device for moving adriven member between at least two predetermined prescribed positions,incorporating a rotational driving source, a reverse input blockingclutch comprising an input member into which torque from the rotationaldriving source is input, and an output member connected to the drivenmember, for transmitting input torque applied to the input member to theoutput member, while blocking the transmission of reverse input torqueapplied at the output member to the input member and permitting theslipping of the output member, and restraining means for elasticallyrestraining the rotation of the output member at each of the prescribedpositions.

According to such a construction, input torque applied from therotational driving source to the input member is transmitted to theoutput member of the reverse input blocking clutch, and this rotationaltorque causes the driven member to move between the two (or three ormore) prescribed positions. When the driven member reaches eachprescribed position, the rotation of the output member is restrainedelastically by the restraining means, and so the driven member resistsexternal forces and is retained in that position. However, if theexternal force becomes very large and the reverse input torque reaches alevel exceeding the elastic rotational restraining force of therestraining means, then the output member overcomes this rotationalrestraining force and begins to rotate. Here, because the reverse inputblocking clutch is of a construction which permits the slipping of theoutput member relative to reverse input torque, this slipping of theoutput member enables the driven member to be freely rotated, and thisfree rotation in turn enables the absorption of the external forceacting upon the driven member. Furthermore, because the reverse inputblocking clutch blocks the transmission of reverse input torque to theinput member, damage to the rotational driving source resulting fromlarge reverse input-torque can be prevented.

In addition, the reverse input blocking clutch may also comprise atorque transmission member which can be engaged with and disengaged fromthe input member and the output member in the directions of both forwardand reverse rotation, a retainer for retaining the torque transmissionmember and controlling the engagement and disengagement of the torquetransmission member through relative rotation relative to the inputmember, a first elastic member for connecting the input member and theretainer in a rotational direction, a stationary member, and rotationalresistance application means for applying sliding frictional resistanceto the retainer for rotation of the retainer relative to the stationarymember.

According to the above construction, when rotational torque from therotational driving source is input at the input member of the reverseinput blocking clutch, the input member and the retainer connected tothe input member begin to rotate via the first elastic member.Accompanying this rotation, a sliding frictional resistance acts uponthe retainer due to the action of the rotational resistance applicationmeans, and consequently the retainer is subject to rotational resistanceand develops a rotational lag, undergoing relative rotation with respectto the input member (at this point, the first elastic member is subjectto elastic deformation). With the-retainer in this state of rotationallag, the torque transmission member engages with both the input memberand the output member, and the rotational torque input at the inputmember is transmitted to the output member via the torque transmissionmember.

In contrast, sliding fractional resistance from the rotationalresistance application means does not act upon the retainer with respectto rotational torque input from the output member (reverse inputtorque), and so the elastic action of the first elastic member causescentering of the retainer. With the retainer in this centered state, thetorque transmission member does not engage with either the input memberor the output member, but remains freely rotatable, and consequently theoutput member is able to slip in a disengaged manner.

The above operation can be achieved by forming a wedge shaped gapbetween the input member and the output member, and then causing anengagement member which functions as the torque transmission member toengage with, or disengage from this wedge shaped gap. This type ofconstruction includes structures in which the cam surface for formingthe wedge shaped gap is provided on either the output member or theinput member (and an engagement member with a circular cross sectionsuch as a roller or a ball is used), and structures in which the camsurface for forming the wedge shaped gap is provided on the engagementmember (and a sprag or the like is used as the engagement member).

The aforementioned restraining means may comprise, for example, aconcave engagement section provided on either one of the output memberor the stationary member, and a convex engagement section provided onthe other member, wherein the engagement section of the stationarymember is positioned over the rotational locus of the engagement sectionof the rotating side, and at each of the prescribed positions theconcave engagement section and the convex engagement section engageelastically, thereby restricting the rotation of the output member.

According to such a construction, if the output member is rotated bytorque applied to the input member, then at the point where the concaveengagement section and the convex engagement section reach opposingpositions, the two sections will elastically engage in a circumferentialdirection, and so rotation of the output member beyond that point isrestricted. However, if a large reverse input torque exceeding therotational restraining force of the restraining means is applied to theoutput member, then the engagement between the concave engagementsection and the convex engagement section releases, and the outputmember begins to slip freely.

This type of construction can be realized, for example, by providing theconcave engagement section on the stationary member, and providing theconvex engagement section on the output member with a second elasticmember disposed therebetween. In such a case, the concave engagementsection and the convex engagement section engage through the elasticforce supplied by the second elastic member. If a large reverse inputtorque exceeding the torque reaction force provided by this elasticforce is applied to the output member, then the output member can becaused to slip, and rotate freely.

If the output member and the stationary member are arranged so as tooppose one another in an axial direction, with the concave engagementsection and the convex engagement section engage positioned within theopposing section, then the restraining means can be integrated withinthe structure of the reverse input blocking clutch, enabling a morecompact overall device to be produced.

In those cases in which a motor is used as the rotational drivingsource, then when the concave engagement section and the convexengagement section engage (not only immediately following engagement,but also immediately prior to engagement), the driving current of themotor increases. Consequently, if the motor is stopped at the point whenthis increase in driving voltage is detected, then the driven member canbe accurately stopped at each of the prescribed positions without theuse of a sensor.

The rotational resistance application means may comprise a slidingmember capable of engaging in a circumferential direction with one ofeither the retainer or the stationary member, and sliding relative tothe other. For example, the sliding member could be provided so as toslide relative to the stationary member while being engaged in acircumferential direction with the retainer.

The driven member could be, for example, a mirror of a vehicle. In sucha case, one of the two prescribed positions could be set as' a workingposition in which the mirror protrudes out from the side of the vehicle,and the other position set as a retracted storage position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a longitudinal sectional view (a cross-sectional view takenalong the line B—B of FIG. 2) of a reverse input blocking clutchaccording to a first embodiment, FIG. 1 b is a transverse sectional viewof a connector, and FIG. 1 c is a view of an output shaft along thedirection of the arrow X in FIG. 1 a;

FIG. 2 is a transverse sectional view (a cross-sectional view takenalong the line A—A of FIG. 1 a) showing the reverse input blockingclutch according to the first embodiment;

FIG. 3 is a perspective view of an input member, an output member and astationary member;

FIG. 4 is an enlarged longitudinal sectional view showing the outerperiphery of torque transmission means (a notch in the input member anda protrusion on the output member);

FIG. 5 is an enlarged longitudinal sectional view showing the outerperiphery of torque transmission means (a notch in the input member anda protrusion on the output member) according to another example;

FIG. 6 a is a front view showing an elastic member, FIG. 6 b is a viewfrom the outer periphery, and FIG. 6 c is an enlarged view showing atongue section positioned between a pair of rollers;

FIG. 7 is a partially enlarged transverse sectional view describing theoperation of the reverse input blocking clutch according to the firstembodiment (neutral position);

FIG. 8 is a partially enlarged transverse sectional view describing theoperation of the reverse input blocking clutch according to the firstembodiment (during lock release);

FIG. 9 is a partially enlarged transverse sectional view describing theoperation of the reverse input blocking clutch according to the firstembodiment (during torque transmission);

FIG. 10 a is a longitudinal sectional view (a cross-sectional view takenalong the line B—B of FIG. 11) of a reverse input blocking clutchaccording to a second embodiment, FIG. 10 b is a transverse sectionalview of a connector, and FIG. 10 c is a view of an output shaft alongthe direction of the arrow X in FIG. 10 a;

FIG. 11 is a transverse sectional view (a cross-sectional view takenalong the line A—A of FIG. 10 a) showing the reverse input blockingclutch according to the second embodiment;

FIG. 12 is a perspective view of an input member, an output member and astationary member;

FIG. 13 is a perspective view of an input member, an output member and astationary member according to another example;

FIG. 14 is a longitudinal sectional view (a cross-sectional view takenalong the line B—B of FIG. 15) or a clutch device;

FIG. 15 is a transverse sectional view (a cross-sectional view takenalong the line A—A of FIG. 14) showing the above clutch device;

FIG. 16 is a schematic illustration showing a rotational driving systemcomprising a motor, a reduction gear, a reverse input blocking clutch,and an output mechanism;

FIG. 17 is a schematic illustration showing a rotational driving systemcomprising a motor, a reduction gear, a reverse input blocking clutch,and an output mechanism;

FIG. 18 is a cross-sectional view of a clutch device;

FIG. 19 is a cross-sectional view of a clutch device, and represents across-section taken along the line B—B in FIG. 20;

FIG. 20 is a cross-sectional view of a clutch device, and represents across-section taken along the line A—A in FIG. 19;

FIG. 21 a is a front view of an input outer ring viewed from a directionA shown in FIG. 21 b, and FIG. 21 b is a cross-sectional view takenalong the line B—B shown in FIG. 21 a;

FIG. 22 is a partially enlarged cross-sectional view showing theoperation (neutral state) of a reverse input blocking clutch;

FIG. 23 a is a cross-sectional view of a retainer, FIG. 23 b is a frontview of the same, FIG. 23 c is a cross-sectional view taken along theline C—C of FIG. 23 a, and FIG. 23 d is a front view viewed from adirection D shown in FIG. 23 a;

FIG. 24 a is a cross-sectional view of a centering spring, and FIG. 24 bis a plan view of the same;

FIG. 25 is a partially enlarged cross-sectional view showing theoperation (sliding spring) of a reverse input blocking clutch;

FIG. 26 is a partially enlarged cross-sectional view showing theoperation (torque transmission state) of a reverse input blockingclutch;

FIG. 27 a is a plan view showing an embodiment of a concave engagementsection, and FIG. 27 b is a cross-sectional view taken along the lineA—A of FIG. 27 a;

FIG. 28 a is a plan view showing an embodiment of a concave engagementsection, and FIG. 28 b is a cross-sectional view taken along the lineA—A of FIG. 28 a; and

FIG. 29 is a perspective view showing an example of an electricretractable mirror.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As follows is first a description, with reference to the drawings, ofembodiments of a clutch (locking type) for blocking the return ofreverse input torque to the input side by locking the output memberrelative to the reverse input torque.

FIG. 1 and FIG. 2 show the overall configuration of a first embodimentof the reverse input blocking clutch described above. The clutch of thisembodiment comprises, as main elements, an input member 1 into whichtorque is input, an output member 2 to which torque is output, astationary member 3 for constraining the revolutions, a fixed side plate4 fixed to the stationary member 3, and locking means, lock releasemeans and torque transmission means which are described below. The inputmember 1, the output member 2, the stationary member 3 and the fixedside plate 4 are formed from metal plates such as press worked steelplates (members formed by press working).

As shown in FIG. 1 and FIG. 3, the input member 1 comprises mainly aflange section 1 a which extends in a radial direction, a cylindricalsection 1 b which extends in a continuous manner in one axial direction(towards the inside of the clutch) from the inner perimeter of the isflange section 1 a, a plurality (eight for example) of pillars 1 c whichextend in a continuous manner in one axial direction from the outerperimeter of the flange section 1 a, and a plurality (eight for example)of apertures 1 d formed in the flange section 1 a.

The pillars 1 c and the apertures 1 d are both positioned withequidistance around the circumference. Moreover, the positions of thepillars 1 c and the positions of the apertures 1 d are mutuallystaggered around the circumference, and in this example an aperture 1 dis positioned centrally between each pair of adjacent pillars 1 c. Thespaces between adjacent pillars 1 c in a circumferential direction forma plurality of pockets 1 e which are open in one axial direction, and apair of rollers 6, which are described below, are positioned within eachpocket 1 e.

The cylindrical section 1 b is positioned inside the clutch, and the tipsection thereof comprises a connector 1 f with a slightly narrowingdiameter. In this embodiment, the internal periphery of the connector 1f is polygonal in shape, such as the square shape shown in FIG. 1 b,with four flat sections 1 f 1 formed by the four sides of the squarerespectively. A connector of an input shaft, not shown in the drawings,(such as the output shaft of a motor or a motor with a reduced gear) isconnected to the connector 1 f. The outer perimeter of the input shaftis of a polygonal shape, such as a square shape, which matches theinternal periphery of the connector 1 f, and has four flat sectionsformed by the four sides of the square respectively. Then, by engagingeach of the flat sections formed on the connector of the input shaftwith each of the flat sections 1 f 1 of the connector 1 f, the inputshaft and the input member 1 are connected in a manner that preventsrelative rotation. Moreover, the connector 1 f may also be shaped sothat not only the inner perimeter, but also the overall shape throughthe thickness of the connector 1 f is a polygonal shape such as a squareshape. Furthermore, the connector of the input shaft and the connector 1f may also be constructed so as to engage via a single flat surfaceprovided on each connector, or via two flat surfaces formed 180° aparton opposing sides of each connector.

The output member 2 comprises mainly a flange section 2 a which extendsin a radial direction, a cylindrical output shaft section 2 b whichextends in a continuous manner in one axial direction (towards theinside of the clutch) from the inner perimeter of the flange section 2a, a large diameter section 2 c which extends from the outer perimeterof the flange section 2 a in a continuous manner in the opposite axialdirection, and a plurality (eight for example) of protrusions 2 d whichprotrude in an axial direction from one edge of the large diametersection 2 c.

One flat surface 2 b 1, for example, is provided at the end of the shaftof the output shaft section 2 b, and this end of the shaft is connectedto a driven member of an output mechanism or a device not shown in thedrawings. Then, by engaging the flat section 2 b 1 at the end of theshaft with a flat section formed on the aforementioned driven member,the output shaft section 2 b and the driven member are connected in amanner that prevents relative rotation. Moreover, the end of the shaftand the driven member may also be constructed so that engagement occursvia a plurality of flat surfaces, by either providing two flat surfaces2 b 1 180° apart on opposing sides of the end of the shaft, or formingthe end of the shaft in a polygonal shape. Furthermore, the end of theshaft of the output shaft section 2 b is closed by an end section 2 b 2.

The large diameter section 2 c is formed in a polygonal shape such as aregular octagon, with the outer surface of each side of the polygonfunctioning as a cam surface 2 c 1. Accordingly, eight cam surfaces 2 c1 are arranged uniformly around the outer periphery of the largediameter section 2 c with an equal spacing between surfaces.

As can be seen in the enlarged view of FIG. 4, each of the protrusions 2d of the output member 2 is inserted into one of the apertures 1 d ofthe input member 1 with a gap in the direction of rotation (therotational gap 62 shown in FIG. 7). Moreover, as shown in FIG. 5, eachaperture 1 d may be subjected to burring, forming a built up section 1 d1. By so doing, the protrusions 2 d and the apertures 1 d can besecurely engaged relative to the direction of rotation.

The stationary member 3 comprises mainly a flange section 3 a whichextends in a radial direction, a cylindrical section 3 b which extendsin a continuous manner in one axial direction from the inner perimeterof the flange section 3 a, a large diameter section 3 c which extendsfrom the outer perimeter of the flange section 3 a in the opposite axialdirection, and a collar section 3 d extending radially outward from oneedge of the large diameter section 3 c.

The flange section 3 a is mounted against the outside surface of theflange section 2 a of the output member 2, and the cylindrical section 3b functions as a bearing (sliding bearing) for supporting the outersurface of the output shaft section 2 b of the output member 2 in amanner which enables free rotation in an axial direction.

The large diameter section 3 c is provided with an inner surface 3 c 1which faces the cam surfaces 2 c 1 of the output member 2 in a radialdirection, forming wedge shaped gaps in the directions of both forwardand reverse rotation.

A plurality (four for example) of rectangular notches 3 d 1 and aplurality (four for example) of circular arc shaped notches 3 d 2 areformed with equidistance around the collar section 3 d. The notches 3 d1 match lugs 4 c provided on the fixed side plate 4 described below. Thenotches 3 d 2 are provided to prevent interference with the mountingbolts fitted to brackets 4 b of the fixed side plate 4.

As shown in FIG. 1 and FIG. 2, the fixed side plate 4 comprises mainly aflange section 4 a which extends in a radial direction, a plurality(four for example) of brackets 4 b which extend radially outward fromthe outer periphery of the flange section 4 a, a plurality (four forexample) of lugs 4 c which extend in one axial direction from the outerperiphery of the flange section 4 a, and a cylindrical section 4 d whichextends in a continuous manner in one axial direction (towards theinside of the clutch) from the inner perimeter of the flange section 4a.

The flange section 4 a is mounted against the outside surface of theflange section 1 a of the input member 1. The four brackets 4 b areformed with equidistance around the periphery of the flange section 4 a,and are each provided with a through hole 4 b 1. Mounting bolts notshown in the drawings are inserted through these through holes 4 b 1.

The four lugs 4 c are also formed with equidistance around theperiphery, and are each equipped with a pair of forked claws 4 c 1(refer to FIG. 2). The lugs 4 c engage in the notches 3 d 1 of thestationary member 3, and the pair of claws 4 c 1 push back in opposingcircumferential directions, thereby fastening onto the collar section 3d of the stationary member 3. As a result, the stationary member 3 andthe fixed side plate 4 are connected in such a manner that preventsrelative movement in both the axial direction and the rotationaldirection.

The cylindrical section 4 d is inserted inside the cylindrical section 1b of the input member 1, and functions as a bearing (sliding bearing)for supporting the outer surface of an input shaft, not shown in thedrawings, in a manner which permits free rotation in a radial direction.

As shown in FIG. 2, a pair of rollers 6 which function as engagementmembers are positioned in each space between the cam surfaces 2 c 1 ofthe output member 2 and the inner surface 3 c 1 of the stationary member3 (giving a total of eight pairs, for example), and these rollers arehoused within the pockets 1 e formed between the pillars 1 c of theinput member 1. A tongue 7 b of an elastic member 7 described below ispositioned between each pair of rollers 6, and pushes the two rollers 6mutually apart the combination of the cam surfaces 2 c 1, the innersurface 3 c 1, the pairs of rollers 6, and the tongues 7 b of theelastic member 7 forms the locking means, whereas the lock release meansis formed from the pillars 1 c (engagement elements) of the input member1 positioned on both sides of each pair of rollers 6 in acircumferential direction, and the torque transmission means is formedfrom the apertures 1 d of the input member 1 and the protrusions 2 d ofthe output member 2 which are inserted therein. Grease or the like maybe used to fill the space between the outer surface of the output member2 and the inner surface of the stationary member 3, particularly thespace between the cam surfaces 2 c 1 and the inner surface 3 c 1.

As shown in FIG. 6, the elastic member 7 is provided with a base 7 a,and tongue sections 7 b extending from the base 7 a in one axialdirection. The elastic member 7 is formed from a single integrated ring,and a plurality of pairs of tongue sections 7 b are positioned withequidistance around the periphery of this ring shaped base 7 a. Theelastic member 7 is formed from a metal plate such as a press workedspring steel plate.

In this embodiment, the outer periphery of the base 7 a is a regularoctagonal shape, with one pair of tongue sections 7 b provided on eachside of this octagon. Each pair of tongue sections 7 b is formed into acurved shape by cutting and lifting a portion of each side of the base 7a, and is connected to the base 7 a via a protruding section 7 c. Asshown in FIG. 6 c, a pair of tongue sections 7 b is sandwiched between apair of rollers 6, and pushes the two rollers 6 mutually apart in anelastic manner.

As can be seen in the enlarged view of FIG. 7, at the neutral position,the pair of rollers 6 are pushed mutually apart by the action of thetongue section 7 b of the elastic member 7, and both engage with thewedge shaped gap formed between the cam surface 2 c 1 and the innersurface 3 c 1 in the directions of both forward and reverse rotation. Atthis time, a gap δ1 exists in the direction of rotation between eachpillar 1 c of the input member 1 and each of the rollers 6. Furthermore,a gap δ2 also exists in the directions of both forward and reverserotation between the protrusion 2 d of the output member 2 and theaperture 1 d of the input member 1. The relationship between therotational gap δ1 and the rotational gap δ2 is such that δ1<δ2. The sizeof the rotational gap δ1 is typically from 0 to 0.4 mm (an angle of 0 to1.5° about the central axis of the clutch), and the size of therotational gap δ2 is typically from 0.4 to 0.8 mm (an angle of 1.8 to3.7° about the central axis of the clutch).

With the device in the state shown in FIG. 7, if a reverse input torqueof a clockwise direction is input at the output member 2, then theroller 6 on the counter clockwise side (the rear roller relative to therotational direction) engages with the wedge shaped gap on that side,and the output member 2 is locked in the clockwise direction relative tothe stationary member 3. If a reverse input torque of a counterclockwise direction is input at the output member 2, then the roller 6on the clockwise side (the rear roller relative to the rotationaldirection) engages with the wedge shaped gap on that side, and theoutput member 2 is locked in the counter clockwise direction relative tothe stationary member 3. Consequently, reverse input torque-from theoutput member 2 is locked by the rollers 6 in the directions of bothforward and reverse rotation.

FIG. 8 shows the initial state in the situation where an input torque(in a clockwise direction in the figure) is input at the input member 1,and the input member 1 begins to rotate in the clockwise direction asshown in the figure. Because the aforementioned rotational gaps are setso that δ1<δ2, first, the pillar 1 c on the counterclockwise side (therear pillar relative to the rotational direction) of the input member 1engages with the roller 6 on that side (the rear roller relative to therotational direction), and presses that roller in a clockwise direction(in the direction of rotation) against the elastic force of the tonguesection 7 b. As a result, this roller 6 on the counter clockwise side(the rear roller relative to the rotational direction) disengages fromthe wedge shaped gap on that side, and the locked state of the outputmember 2 is released. {Moreover, the roller 6 on the clockwise side (thefront roller relative to the rotational direction) does not engage withthe wedge shaped gap on that side}. Consequently, the output member 2 isable to rotate in a clockwise direction.

If the input member 1 rotates further in the clockwise direction, thenas shown in FIG. 9, the surface wall of the aperture 1 d of the inputmember 1 engages with the protrusion 2 d of the output member 2 in aclockwise direction. As a result, the clockwise input torque from theinput member 1 is transmitted to the output member 2 via this engagementbetween the aperture 1 d and the protrusion 2 d, and the output member 2begins to rotate in a clockwise direction. In the case in which acounter clockwise input torque is input at the input member 1, then theopposite operation to that described above results in the output member2 rotating in a counter clockwise direction. Accordingly, input torquefrom the input member 1 in either the forward or the reverse rotationaldirection is transmitted to the output member 2 via the torquetransmission means comprising the apertures 1 d and the protrusions 2 d,and results in the output member 2 rotating in either the forward or thereverse rotational direction. Moreover, when the input torque from theinput member 1 disappears, the rollers 6 and the input member 1 returnto the respective neutral positions shown in FIG. 7 under the effect ofthe elastic restoring force of the tongue sections 7 b.

FIG. 10 to FIG. 12 show a second embodiment of the present invention.This second embodiment differs from the first embodiment described abovein that the torque transmission means employs an engagement structurecomprising notches 21 d and protrusions 22 d which project radiallyoutward. As shown in FIG. 12, the notches 21 d are formed in the outeredge of the flange section 1 a of the input member 1. A plurality (eightfor example) of notches 21 d are formed, and these are arranged withequidistance around the periphery of the flange section 1 a. The baseends 1 c 1 of the pillars 1 c are slightly wider in a circumferentialdirection than the tips, and the notches 21 d are positioned betweeneach set of adjacent base ends 1 c 1. The radially outward projectingprotrusions 22 d are formed as a continuation of the large diametersection 2 c of the output member 2, linked by axial direction base ends22 d 1. A plurality (eight for example) of protrusions 22 d are formed,and these are arranged with equidistance around the periphery of thelarge diameter section 2 c. Each of the protrusions 22 d of the outputmember 2 fits into one of the notches 21 d, with a gap δ2 in thedirection of rotation (refer to FIG. 7).

Moreover, instead of the notches 21 d, the input member 1 may also beprovided with notches 21 d′ of the shape shown in FIG. 13. According tothis example, unlike the notch shape shown in FIG. 12, the flangesection 1 a of the input member 1 need not be subject to notching, andconsequently the production process is simpler. Furthermore, the torquetransmission means could also be achieved by fitting together thenotches provided in the input member 1 and axial protrusions provided onthe output member 2, with a gap δ2 in the direction of rotation (referto FIG. 7). The remaining details of the construction of the embodimentare identical with those described for the first embodiment, and as suchare omitted here.

According to the present invention, a reverse input blocking clutch canbe provided which incorporates a function for transmitting input torquefrom the input side to the output side while locking reverse inputtorque from the output side and preventing such reverse torque returningto the input side, and which is moreover compact, lightweight, and cheapto produce.

FIG. 14 and FIG. 15 show the overall structure of a clutch device whichemploys a reverse input blocking clutch C (lock type) as describedabove. This clutch device is assembled into a single unit comprising amotor M, a reduction gear R, and the reverse input blocking clutch C.This clutch device functions as a rotational driving device forgenerating rotational torque, and torque generated by the motor M isdecelerated by the reduction gear R, and is subsequently transmittedfrom an output shaft R1 of the reduction gear R, through the reverseinput blocking clutch C, and input into an output side mechanism O(refer to FIG. 17 and FIG. 18). In terms of the vehicle mirror drivingdevice mentioned above, the mirror to be driven (such as a door mirror)would correspond with the output side mechanism O.

The reverse input blocking clutch C comprises, as main elements, aninput member 1 into which torque from the reduction gear R is input, anoutput member 2 to which torque is output, a stationary member 3 forconstraining the revolutions, a fixed side plate 4 fixed to thestationary member 3, and locking means, lock release means and torquetransmission means which are described below.

The output shaft R1 of the reduction gear R is inserted into a connector1 f of the input member 1. The outer periphery of the tip of the outputshaft R1 is a polygonal shape, such as a square shape, which correspondswith the internal surface of the connector 1 f, and each side of thesquare forms one of four flat surfaces. Engagement between each of theflat surfaces formed on the output shaft R1 with the corresponding flatsurfaces 1 f 1 of the connector 1 f causes the output shaft R1 and theinput member 1 to be connected in such a manner that prevents relativerotation.

An output shaft section 2 b of the output member 2 is connected to thedriven member (not shown in the drawings) of the output side mechanismO. In this embodiment, the example is shown in which the end section ofthe output shaft section 2 b is a circular cylindrical surface, althougheither one, or a plurality of flat surfaces 2 b 1 can also be formed onthis end section, in the same manner as was shown in the firstembodiment. By attaching installation bolts inserted in the throughholes 4 b 1 of the fixed side plate 4, to a member (a frame or housing)of the reduction gear R, the reverse input blocking clutch C can befixed directly to the reduction gear R. The device for fixing thereverse input blocking clutch C to the reduction gear R is notrestricted to bolts however, and any other suitable device can also beselected. Moreover, the reverse input blocking clutch C can also befixed to a commercially available reduction gear motor in which themotor M and the reduction gear R have already been assembled.

The remaining construction and the operation of the reverse inputblocking clutch C are identical with the embodiments described in FIG. 1through FIG. 13, and as such are not described here.

In the above description, and as is also shown in FIG. 16, the examplewas described wherein the motor M, the reduction gear R and the reverseinput blocking clutch C of the rotational driving system for driving theoutput side mechanism O with the rotational torque from the motor M wereincorporated within a single unit (the unit is shown with a dotted linein the figure). However, as shown in FIG. 17, a clutch device whichoperates on receiving rotational torque can also be constructed byseparating the reverse input blocking clutch C from the reduction gear Rand integrating the clutch into a unit with the output side mechanism O.In such a case, the construction of the reverse input blocking clutch Cconforms with the construction of the clutch device described in FIG. 1through FIG. 15. In such a case, the connector 1 f of the input member 1is connected to a transmission shaft 10 which extends out from theoutput side of the reduction gear R, and the output shaft section 2 b ofthe output member 2 is connected to the input side (the driven member)of the output side mechanism O.

The reverse input blocking clutch described above is not restricted touse in only vehicle mirror driving devices, and can also be used in awide variety of other mechanisms and devices. Other examples includefolding devices (such as a bed, a seat or the joints of a robot) whichgenerate an angular displacement, raising and lowering devices (such asan elevator, a jack, or the window glass in a vehicle) which generate alinear displacement, opening and closing devices (such as a door, ashutter, a sunroof, or an electric sliding door), and rotational devices(such as an electric power steering device, a bicycle sprocket, anelectric wheelchair, an electric vehicle, and the rear wheels of avehicle with four wheel steering [which uses a ball screw]).Specifically, in the feed screw section of a machine tool or controldevice, or in the ball screw section of a nursing bed or a home elevatordriven by a ball screw, by positioning a reverse input blocking clutch Cbetween the screw section and the motor, the output member 2 can belocked with respect to reverse input torque from the screw section(which corresponds with the driven member or the output side mechanismO), thereby preventing reverse input torque returning to the motor sideof the device.

Furthermore, in tools such as electric drivers and the like, if areverse input blocking clutch C described above is positioned betweenthe motor and the chuck, then the output member can be locked withrespect to reverse input torque applied by the chuck, and so havingscrewed in a screw electrically, the screw can be further tightened byhand (by rotating the entire tool), thereby increasing the functionalityof the tool.

Furthermore, in the case of power seats or power windows in vehicles, areverse input blocking clutch C such as that described above can also bepositioned between the motor and the seat (or the window). In suchmechanisms, a worm and wheel mechanism is often used as a reduction gearfor preventing the return of reverse input torque from the seat or thewindow to the motor, although because the torque transmission efficiencyof a worm and wheel mechanism is quite poor, the capacity of the motorneeds to be increased. In contrast, if a reverse input blocking clutchis used, then return of reverse input torque from the seat or the likecan be prevented in a similar manner, and so a spur gear or the like,with a better transmission efficiency than a worm and wheel mechanism,can be used, meaning the capacity of the motor can be minimized.

Furthermore, a reverse input blocking clutch as described above can alsobe installed in the rotational drive section of the C arm of an X-rayinspection device. The C arm is a C shaped member with an X-rayirradiation section and a receiver section, and during inspection this Carm is rotated around the object being inspected so that imaging can beconducted from any position. By positioning a reverse input blockingclutch C as described above between this C arm and the motor,fluctuations of the C arm can be suppressed, enabling more preciseimaging to be conducted.

Furthermore, in vehicles such as motorbikes, buggies and tractors, kickback from the surface of the road during traveling transfers to thehandles or steering wheel. In such cases, if a reverse input blockingclutch C described above is positioned between the steering shaft andthe axle shaft, then kick back can be suppressed, enabling animprovement in steering stability.

According to the present invention, because the rotational drivingsource comprising the motor and the reduction gear, and the clutch (orthe clutch and the output mechanism) are produced as a single integratedunit, a compact and lightweight clutch device can be provided. Thisclutch device incorporates a function for transmitting input torque fromthe input side to the output side while locking reverse input torquefrom the output side and preventing such reverse torque returning to theinput side, and consequently reverse input torque does not generate anyrotation within the rotational driving source. Accordingly, deleteriouseffects on the reduction gear and the motor resulting from excessivereverse input torque can be prevented, making the invention suitable forapplications in which positional displacement of the output mechanismresulting from reverse input torque is undesirable.

Next is a description of a clutch device using a free type clutch forblocking the return of reverse input torque to the input side byallowing the output member to freely rotate with respect to such reverseinput torque.

FIG. 18 shows one embodiment of this type of clutch device. As shown inthe figure, this clutch device comprises a reverse input blocking clutchC, restraining means 20, and a motor M which functions as a rotationaldriving source. Rotational torque from the motor M is transmitted viathe reverse input blocking clutch C to a mirror 30 which functions asthe driven member, and this mirror is able to be swung in both theforward and reverse directions about a swing axis P. The restrainingmeans 20 holds the mirror 30 at a predetermined storage position and aworking position.

As shown in FIG. 19 and FIG. 20, the reverse input blocking clutch Ccomprises an input outer ring 11 which functions as an input member, anoutput inner ring 12 which functions as an output member, rollers 13which function as torque transmission means, a retainer 14 for retainingthe rollers 13, a centering spring 15 which functions as a first elasticmember for positioning the retainer 14, first and second side plates 16a, 16 b which function as a stationary member, and a sliding spring 17which functions as rotational resistance application means for applyingsliding frictional resistance to the retainer with respect to rotationof the retainer 14. Input torque from the motor M is input at the inputouter ring 11, and is transmitted through the rollers 13 and output fromthe output inner ring 12. As is shown in FIG. 18, the rotational shaftof the mirror 30 is connected to the output inner ring 12.

In the following description, for the sake of convenience, the rightside of the FIG. 19 is referred to as “one edge” or “one side”, and theleft side of the figure is referred to as the “other edge” or the “otherside”.

A toothed section 11 b is formed at the outer periphery of one edge ofthe input outer ring 11. As shown in FIG. 18, this toothed section 11 bmeshes with a driving gear 5 attached to the output shaft of the motor Mto form the reduction gear R. The reduction gear R is not restricted tothe configuration shown in the figure, and may adopt any suitableconfiguration. The toothed section 11 b may be formed directly on theouter periphery of the input outer ring 11 using a metallic materialsuch as hardened steel, or may also be formed as a separate member whichis subsequently fixed to the outside of the input outer ring 11. In sucha case, the toothed section 11 b could be made of a resin and the inputouter ring 11 manufactured from a metallic material such as hardenedsteel, with the two components then being integrated into a single unitusing pressure, an engagement between mating ribbed surfaces, or insertmolding.

As shown in FIG. 21, a collar 11 c which protrudes radially inward isformed on one edge of the inner perimeter of the input outer ring 11. Atone position in the circumference of this collar 11 c, a notch 11 d isformed which extends the entire length of the collar 11 c in an axialdirection.

As shown in FIG. 19 and FIG. 20, the output inner ring 12 is positionedinside the input outer ring 11. This output inner ring 12 comprises acylindrical section 12 a facing the inner surface of the input outerring 11, and a shaft section 12 b which extends out in an axialdirection. In this embodiment, the outer periphery of the cylindricalsection 12 a is formed in a circular cylindrical shape.

As shown in FIG. 22, the inner surface of the input outer ring 11 isprovided with a plurality (the same number as the number of rollers 13)of cam surfaces 11 a, which are formed with equidistance around theperiphery, and which together with the outer surface of the cylindricalsection 12 a of the-output inner ring 12 form wedge shaped gaps s1 whichreduce in width symmetrically in both the forward and reverse rotationaldirections. Each wedge shaped gap s1 has a width at the center pointthereof in a circumferential direction c1 which is larger than thediameter of the roller 13, and the wedge shaped gap s1 reduces in widthsymmetrically in both the forward and reverse rotational directions fromthis circumferential center point c1. When the roller 13 is positionedat the circumferential center point c1 of the wedge shaped gap s1, theroller 13 is able to rotate freely within the wedge shaped gap s1.

The retainer 14 is a circular cylinder, and is positioned between theinner surface of the input outer ring 11 and the outer surface of thecylindrical section 12 a of the output inner ring 12, with the rollers13 retained in a plurality of pockets 14 a formed with equidistancearound the periphery of the retainer 14. As shown in FIG. 23, an axialdirection notch 14 b for accommodating the centering spring 15 is formedin the axial end surface on one side of the retainer 14, and a notch 14c which extends in a circumferential direction is formed in the axialend surface on the other side. In the example shown in the figures, thenotches 14 b, 14 c are positioned 180° apart in radially opposingpositions. The other axial end surface of the retainer 14 protrudesfurther than the other end surface of the input outer ring 11, and thenotch 14 c extending in a circumferential direction is formed in thisprotruding section.

As shown in FIG. 24, the centering spring 15 is constructed from a platespring which is bent to a substantially U shape. As can be seen in FIG.19 and FIG. 20, once the positions of the notch 11 d in the input outerring 11 and the notch 14 b in the retainer 14 have been aligned in acircumferential direction, this centering spring 15 is engaged into boththese notches lid, 14 b, with the two tips of the U shape able to expandand contract in a circumferential direction, and with the bottom 15 a ofthe U shape facing inward. This centering spring 15 performs thefunction of elastically connecting the retainer 14 and the input outerring 11 in a rotational direction, and also performs the function ofpositioning (centering) the retainer 14 with respect to the input outerring 11 so that the rollers 13 accommodated within the pockets 14 a ofthe retainer 14 are positioned at the respective circumferential centerpoints c1 of the wedge shaped gaps s1. FIG. 22 shows the state in whichthe retainer 14 has been centered by the centering spring 15, and inthis state, the circumferential centers of the pockets 14 a of theretainer 14 coincide with the circumferential center positions of thecam surfaces 11 a of the input outer ring 11, and the roller 13 arepositioned at the respective circumferential center points c1 of thewedge shaped gaps s1.

The first side plate 16 a and the second side plate 16 b are members ofthe stationary system (the member which does not rotate), and are formedfrom either press worked metal plate or molded resin. As shown in FIG.19, these two side plates 16 a, 16 b are fastened together as a singleunit using bolts or the like, with-the structural elements of the clutch(the input outer ring 11, the output inner ring 12, the rollers 13; theretainer 14, the centering spring 15 and the sliding spring 17) housedbetween the two plates.

The first side plate 16 a comprises a cylindrical section 16 a 1 forhousing the other end of the retainer 14 and the sliding spring 17, anda support section 16 a 2 which extends radially inward from the otheredge of the cylindrical section 16 a 1. The support section 16 a 2 facesthe edge surface of the cylindrical section 12 a of the output innerring 12 in an axial direction, and the inner surface of the supportsection 16 a 2 is pressed against the edge surface of the cylindricalsection 12 a. The second side plate 16 b comprises a cylindrical section16 b 1 for housing the input outer ring 11, and a support section 16 b 2positioned inside the cylindrical section 16 b 1. The shaft section 12 bof the output inner ring 12 is inserted inside the support section 16 b2, and this support section 16 b 2 functions as a bearing (a slidingbearing) for supporting the shaft section 12 b in such a manner thatallows free rotation in a radial direction. A portion of the cylindricalsection 16 b 1 of the second side plate 16 b is cut away, and withinthis cut away portion, the toothed section 11 b of the input outer ring11 meshes with the driving gear 5 shown in FIG. 18.

The sliding spring 17 is a sliding member which slides relative to thefirst side plate 16 a, and in this particular embodiment is formed as anopen ring shaped spring member. As can be seen in FIG. 25, this slidingspring 17 comprises a ring shaped sliding section 17 a, and engagementsections 17 b, 17 c formed by bending the two tips of the slidingsection 17 a radially inwards. The sliding section 17 a is squeezedslightly closed and pushed inside the inner perimeter of the of thecylindrical section 16 a 1 of the first side plate 16 a, and is held inelastic contact with the inner surface of the cylindrical section 16 a1. The engagement sections 17 b, 17 c are both inserted into the notch14 c extending in a circumferential direction around the other edge ofthe retainer 14, and in this state, the distance between the engagementsections 17 b, 17 c in a circumferential direction is smaller than thecircumferential length of the notch 14 c.

As follows is a description of the operation of the reverse inputblocking clutch C.

In the initial state prior to the input of rotational torque at theinput outer ring 11, the retainer 14 is centered by the centering spring15 as shown in FIG. 22. Consequently, the rollers 13 accommodated withinthe pockets 14 a of the retainer 14 are positioned at thecircumferential center points c1 of the wedge shaped gaps s1 formedbetween the cam surfaces 11 a of the input outer ring 11 and thecylindrical section 12 a of the output inner ring 12.

If a rotational torque in a clockwise direction as shown in the figuresis input from the motor M to the input outer ring 11, then the centeringspring 15 causes the retainer 14 attached to the input outer ring 11 tobegin rotation together with the input outer ring 11. Then, when theretainer 14 has rotated through a predetermined angle, the rear edgesurface 14 d relative to the rotational direction, defining the notch 14c of the retainer 14 contacts the rear engagement member 17 c of thesliding spring 17 relative to the rotational direction, as shown in FIG.25.

If the input outer ring 11 then rotates even further, the edge surface14 d of the retainer 14 engages with the engagement member 17 c of thesliding spring 17 and causes the sliding spring 17 to also rotate. Atthis point, the sliding spring 17 slides around the inner perimeter ofthe cylindrical section 16 a 1 of the first side plate 16 a and issubjected to sliding frictional resistance from the stationary side.This sliding frictional resistance is transmitted to the retainer 14 viathe engagement member 17 c, and acts as resistance to the rotation ofthe retainer 14. Provided the rotational resistance (torque) on theretainer 14 resulting from the sliding frictional resistance of thesliding spring 17 is set to a greater value than the elasticity (springtorque) of the centering spring 15, then the centering spring 15undergoes an elastic deformation, and the retainer 14 develops arotational lag relative to the input outer ring 11 equivalent to theamount of elastic deformation.

As a result of this rotational lag of the retainer 14, the roller 13held within the pocket 14 a becomes wedged in the wedge shaped gap s1between the cam surface 11 a of the input outer ring 11 and the outersurface of the cylindrical section 12 a of the output inner ring 12, asshown in FIG. 26. Consequently, the rotational torque input at the inputouter ring 11 is transmitted to the output inner ring 12 via the roller13. In the case in which a rotational torque in a counter clockwisedirection is input to the input outer ring 11, the reverse operations tothose described above result in the output inner ring 12 rotating in acounter clockwise direction.

When the input outer ring 11 stops, the restoring force of the centeringspring 15 causes the roller 13 to disengage from the wedge shaped gap s1and return to the circumferential center point c1 of the wedge shapedgap s1. In those cases in which the engagement force (the residualtorque) acting upon the roller 13 is large, so that the roller 13 stayswedged within the wedge shaped gap s1 even after the input outer ring 11has stopped, the roller 13 can be disengaged from the wedge shaped gaps1 by applying a rotational torque in a counter clockwise direction (theopposite direction to the input rotational torque) to the input outerring 11.

In contrast, in the case in which a reverse input torque is applied tothe output inner ring 12 from the mirror 30, the sliding frictionalresistance of the sliding spring 17 is not produced, and so the retainer14 is held in a centered state (refer to FIG. 22) by the centeringspring 15. In this centered state, because the roller 13 is positionedin the circumferential center of the wedge shaped gap s1, the roller 13is able to rotate freely. As described above, this enables the outputinner ring 12 to slip freely, thereby blocking the transmission of thereverse input torque to the input side.

The restraining means 20 is a device for holding the mirror 30 in astorage position or a working position, by causing an elastic engagementbetween a concave engagement member 21 provided on either one of thestationary member and the output inner ring 12, and a convex engagementmember 22 provided on the other member.

In FIG. 19, the example is shown in which concave engagement members 21are formed on the support section 16 a 2 of the first side plate 16 awhich functions as the stationary member, and convex engagement members22 are formed on the opposing cylindrical section 12 a of the outputinner ring 12. Each concave engagement member 21 is formed by, forexample, creating a depression in the inner surface of the supportsection 16 a 2 of the first side plate 16 a, and these depressions areformed in four positions spaced at equal 90° intervals in acircumferential direction (refer to FIG. 27 a). Each convex engagementmember 22 is formed from a steel ball, for example, which is housedwithin an axial direction aperture 23 formed in the end surface of thecylindrical section 12 a of the output inner ring 12, and retained inplace by a second elastic member 24 comprising a coiled spring or thelike. In this embodiment, convex engagement members 22 are provided atfour positions spaced at equal 90° intervals in a circumferentialdirection, in the same manner as the concave engagement members 21. Theconvex engagement members 22 are permanently pressed against the surfaceof the support section 16 a 2 by the elastic force of the elasticmembers 24, and each of the concave engagement members 21 is positionedat a point within the rotational locus of a convex engagement member 22.Consequently, each convex engagement member 22 either slides or rollsacross the inner surface of the support section 16 a 2 as the outputinner ring 12 rotates, and upon reaching a concave engagement member 21,projects outward and engages elastically with that concave engagementmember 21.

In the above construction, when the mirror 30 is either opened from thestorage position to the working position, or closed from the workingposition back to the storage position, then at the point where themirror 30 has undergone a rotation of approximately 90°, the concaveengagement members 21 and the convex engagement members 22 engageelastically, retaining the mirror 30 at one of the respective positions.Because the aforementioned reverse input blocking clutch C which enablesthe output inner ring 12 to slip freely with respect to a reverse inputtorque is connected to the mirror 30, there is a danger that vehiclevibrations or wind pressure during operation of the vehicle may causethe mirror 30 to rotate, producing a positional displacement. However,because a clutch device according to the present invention is alsoprovided with the aforementioned restraining means 20, the mirror 30 isable to overcome this type of external force, and remain reliably fixedat each of the prescribed positions.

During driving of the motor M, when the concave engagement members 21and the convex engagement members 22 coincide, the convex engagementmembers 22 are forced into the corresponding concave engagement members21, and the engagement of the two sets of members determines therotational angle. At this point, the increase in torque will cause anincrease in the driving current within the motor M, and by detectingthis current increase, a determination can be made that the mirror 30has reached the storage position or the working position, and the motorM can then be stopped based on this information. Consequently, therotational angle can be detected without the need to provide a separaterotational angle detecting mechanism with a sensor or the like, therebyenabling a low cost electric retractable mirror of compact constructionto be provided.

In those cases in which the mirror 30 contacts a pedestrian or anobstacle or the like, and the output inner ring 12 is subjected to alarge reverse input torque exceeding the spring sliding torque of thesecond elastic member 24, the convex engagement members 22 are pushed upover the level difference provided by the concave engagement members 21and disengage from the concave engagement members 21. Followingdisengagement, the output inner ring 12 slips freely, thereby absorbingthe external force, and so damage to the mirror 30 can be prevented. Atthis time, the reverse input torque is not transmitted to the motor M orthe reduction gear R, and so damage to these mechanisms can also beprevented.

In addition to the method described above, in which the concaveengagement members 21 were formed by creating partial depressions in theinner surface, the concave engagement members 21 can also be generatedby forming circular protrusions 26 a on the inner surface, as shown inFIG. 27. In such a case, the increase in the motor current value willbegin before the engagement of the engagement members 21, 22, and soreliable engagement of the engagement members 21, 22 can be ensured bystopping the motor M at the point where the current value has peaked andis beginning to decline. FIG. 28 shows an example in which the concaveengagement members 21 are produced by forming two linear protrusions 26b which are orthogonal to the rotational direction of the convexengagement members 22.

In this embodiment, the concave engagement members 21 are provided onthe first side plate 16 a of the stationary side, and the convexengagement members 22 are provided on the output inner ring 12 of therotating side, but the opposite case is also possible, wherein theconcave engagement members 21 are provided on a rotating member (such asthe output inner ring 12) and the convex engagement members 22 areprovided on a stationary member (such as the first side plate 16 a).Furthermore, in this embodiment four of each of the concave engagementmembers 21 and the convex engagement members 22 were provided, butprovided one of either the convex or concave members is provided at twopositions separated by 90°, one or more of the other members willsuffice.

In the above description, the mirror section of an electric retractablemirror of a vehicle was used as an example of the driven member, butprovided the driven member is an object to be positioned in at least twoprescribed positions, then any member can be used as the driven member.Suitable alternative examples include opening and closing devices (suchas a door, a shutter, a sunroof, or an electric sliding door) which areopened and closed between two prescribed positions. Moreover, the numberof prescribed positions for positioning the driven member is not limitedto two, and devices with three or more positions are also possible. Insuch cases, the number of engagement positions for the concaveengagement members 21 and the convex engagement members 22 must also beincreased or decreased in accordance with the number of positioningpositions.

As described above, according to the present invention, a reverse inputblocking clutch transmits input torque from a rotational driving sourceto a driven member, while blocking the transmission of reverse inputtorque applied to the output member back to the input member.Consequently, the input side (the motor and the reduction gear and thelike) is not subjected to reverse driving arising from reverse inputtorque from the output member, and so damage to the members on the inputside can be prevented. Furthermore, if the reverse input torque issmall, the driven member is retained at-a prescribed position, whereasif the reverse input torque is large, the output member is allowed toslip freely, thereby absorbing the impact of the external force andpreventing damage to the driven member such as a mirror.

In addition, in those cases in which the mechanism disclosed in theabove publication (Japanese Patent Laid-Open Publication No. Hei11-51092) is actually employed within an electric retractable mirror,then the rotational angle of the mirror must be detected, and the motorstopped when the mirror is detected as having reached the storageposition or the working position. As a result, a sensor for detectingthe rotational angle and a control system for processing the detectionsignals must also be provided, which leads to a more complicatedstructure, whereas in the present invention, this detection and controlis performed by restraining means which utilizes elastic force, and sosuch complicated structures are unnecessary.

1. A method of manufacturing a reverse input blocking clutch, the clutchcomprising: an input member into which torque is input, an output memberto which torque is output, a stationary member, locking means providedbetween said stationary member and said output member for locking saidoutput member and said stationary member with respect to reverse inputtorque from said output member, lock release means provided on saidinput member for releasing a locked state produced by said locking meanswith respect to input torque from said input member, and torquetransmission means provided between said input member and said outputmember for transmitting input torque from said input member to saidoutput member when a locked state produced by said locking means isreleased, said torque transmitting means including a protrusion providedon the output member and an edge of a notch or an opening provided onthe input member to engage said protrusion, wherein the method comprisesthe step of: producing said input member and said output member fromamongst said input member, said output member and said stationary memberby press working of a metal plate.